Design and experimental implementation of a quasi-direct-drive leg for optimized jumping

This paper introduces a novel method for actuator design that exploits electromagnetic motors' torque and speed potential in jumping applications. We proposed a nonlinear optimization process that integrates (a) the control design to obtain the optimal ground reaction force, and (b) the mechanical design to narrow down the choices of motor/gearbox pair. Based on this method, actuators were designed and assembled into a leg prototype with two actuated degrees of freedom. Experiments demonstrated that the leg could achieve a maximum vertical jumping height of 0.62 m (2.4 times of leg length) and maximum forward jumping distance of 0.72 m (2.7 times of leg length).